The current invention is directed to the detection of trace amounts of a target analyte. In particular, the present invention provides preconcentrator media in particulate form suitable for use in a preconcentrator coupled with an analyte detector.
Additionally, the current invention provides methods for preconcentration of an analyte for subsequent detection by a detector. Trace quantities of analytes such as volatile organic compounds, drugs, explosives and other hazardous materials are difficult to detect by conventional techniques. Improving the sensitivity of the detector device is not always practical and can be expensive. Further, conducting such tests outside the laboratory requires the use of portable detectors which frequently are not as sensitive as laboratory based equipment. To overcome these difficulties, preconcentrators have been developed to enhance or increase the concentration of the target analyte in a given volume of a sample for analysis by the detector. While preconcentrators are currently available, they generally rely upon analyte collectors comprising adsorbent material packed into a tube through which the fluid containing the analyte is flowed. However, currently available preconcentrators commonly desorb the analyte from the adsorbent material by application of resistive heating to heat the tube and the adsorbent material to thermally desorb the collected analyte. This design requires high powers and provides relatively slow heating, limiting the concentration enhancement that can be achieved. It is also subject to significant thermal grading affects resulting in overheating and/or non-uniform heating of the adsorbent. Thus, desorption of the analyte is inconsistent and relatively uncontrolled.
The present invention overcomes the difficulties of the prior art by providing preconcentrator media in the form of particles that include heatable cores. As described below, the particles are designed to capture a wide variety of analytes. Additionally, the preconcentrator media of the current invention provides rapid heating, leading to large concentration enhancements, and enhanced control of the desorption process. Thus, use of the preconcentrator media of the current invention enhances the detection of trace analytes.